Electronics!

Even though I was an Electrical Engineer, I never was one for electronics.  But since I’ve been in a lab, and needing it to run experiments, I’ve become a recent convert.  I blame Cornell’s ECE 210/215.  Those classes (when I took them) were more about “what’s the voltage here” and “the current there,” rather than developing electronics to do things.

For example, in this lab, I needed a PID controller for Laser frequency stabilization.  Basically, the frequency of the laser drifts, and we need to control it, using a feedback loop.  Basically, the PID controller adds a correction to the current in the laser diode (which determines the frequency of the laser) .  This correction is a sum of a proportional signal (i.e. what’s going on right now—are we too high? or too low?), an integral signal (in the long-term, what’s its tendency to do?), and a derivative signal (right now, are we drifting away from where want to be? or towards?).

This provides an actual purpose to the circuit.  Can I build a proportional signal?—yes, that’s just an amplifier with adjustable gain.  I can build an integrating circuit, and a differentiating circuit as well.  But before, I never had any reason to build them.  They were just simple circuits that did what they did, and that was that.

That’s what was missing in my intro circuits class.  I never felt that the circuits we made were to do things.  We made circuits, and tested to see how they behaved.  Which, quite frankly, didn’t interest me at all.